"Elizabeth Anania Edwards, mother, author, advocate died today at her home in Chapel Hill, surrounded by her family," said a statement released by her family. "Today we have lost the comfort of Elizabeth's presence but she remains the heart of this family."

"We love her and will never know anyone more inspiring or full of life," the statement read.

Edwards passed away at 10:15 a.m. this morning as a result of liver failure, but the family did not release the news until late in the day because her children were at school, a close friend of the family told ABC News.

Edwards, who was estranged from her husband and one-time presidential hopeful John Edwards, was first diagnosed with breast cancer in 2004. The cancer returned in 2007, and earlier this week it was announced the she had stopped all cancer treatment.

The family friend said that even Edwards was surprised at how fast her illness progressed in her final days. Doctors had told her just last week that she could have as many as eight weeks to live.

John Edwards and her three children were among those at her side, according to the family friend, who described the environment in the house as warm and peaceful and said the mood was sad, but also full of warm feelings.

The funeral is likely to be held later this week.

"On behalf of Elizabeth we want to express our gratitude to the thousands of kindred spirits who moved and inspired her along the way. Your support and prayers touched our entire family," read the family statement after Edwards' death.

Just one day before losing her battle to cancer, Edwards wrote a moving message on her Facebook page.

"You all know that I have been sustained throughout my life by three saving graces ? my family, my friends, and a faith in the power of resilience and hope," she wrote. "These graces have carried me through difficult times and they have brought more joy to the good times than I ever could have imagined."

"The days of our lives, for all of us, are numbered. We know that. And, yes, there are certainly times when we aren't able to muster as much strength and patience as we would like. It's called being human," wrote Edwards.

"But I have found that in the simple act of living with hope, and in the daily effort to have a positive impact in the world, the days I do have are made all the more meaningful and precious. And for that I am grateful."

President Barack Obama called John Edwards and his daughter Cate this afternoon after Elizabeth Edwards passed away.

"In her life, Elizabeth Edwards knew tragedy and pain. Many others would have turned inward; many others in the face of such adversity would have given up. But through all that she endured, Elizabeth revealed a kind of fortitude and grace that will long remain a source of inspiration," Obama said in a statement released by the White House.

John Edwards was campaigning for the Democratic presidential nomination when his wife's cancer returned in 2007.

Elizabeth Edwards Dies at Age 61

"Her cancer is back. We are very optimistic about this," he said at the time.

But the stage-four cancer was deemed incurable, and within a year Edwards was fighting another battle. It was revealed that her husband had a sexual relationship with filmmaker Rielle Hunter.

Edwards recounted the situation her book, "Resilience," and spoke about the revelation with Oprah Winfrey.

"It was...it was just a really tough. That was a really tough night," she told Winfrey.

In January, the couple separated after 30 years of marriage after John admitted he had fathered a daughter with Hunter.

Born Mary Elizabeth Anania, Elizabeth Edwards grew up in Virginia as the daughter of a navy pilot.

She initially planned to teach literature, but ultimately pursued a law degree at the university of North Carolina, where she met John.

The couple had four children.

Their oldest son, Wade, was killed in an automobile accident in 1996 at the age of 16.

"When Wade died, it was -- it was a terrible burden," she said on Larry King Live. "But it also reminded you both of the fact that you needed to grab hold of each day. You couldn't -- you couldn't just take each day for granted."

In recent years, Elizabeth authored two best-selling books and became a champion of causes involving poverty and cancer.

But always, she said, her children were her top priority: 28-year-old Cate, 12-year-old Emma Claire and 10-year-old Jack.

"It scares me the most that there's going to be a day that, you know, is likely to come before I wanted it to come where I have to tell these sweet children goodbye," she said in a Nightline interview.

Children Are Top Priority

In an April 2008 interview with "Good Morning America's" Robin Roberts, she said wanted her children to be able to handle any situation that comes their way.

"They have to know how to fly by themselves. They have to know what to do when the wind blows them off course. And that's what's happened to me," she said. "The wind has blown me off course, but I'm kind of thinking this might be it. That, in bad times, you still keep your eye on what it was that was important to you. And you press forward with that. And if - that's all I give them, then I would have done a really great job."

Life Goes On

In a television appearance taped in July on the "Nate Berkus show," she talked about talking about her new furniture store in North Carolina.

"It's unlike anything I've lived before. I was sort of an at-home mother for a while, and then a political wife," she said. "So now, this is the next phase and it belongs to me. It doesn't belong to any of those things in the past."

Weeks earlier, she appeared on CNN's "Larry King Live."

"I don't think that I'm special in any way, but I think most people do pull themselves together. Do what it is they need to be done," she said. "Sometimes you're thrown for a loop for a little while and then you start to reclaim."

She told King she wanted to live eight more years to see her young children grow up.

"I'd like for them to see me seeing them off in their new life. So they -- as adults, they would see me as still, a presence in their life and not as that distant memory of the -- you know, the woman playing Legos with them on the floor, but somebody who was a real part of their lives," she said.

Sen. John Kerry, D-Mass., John Edwards' former running mate in 2004, said in a statement that he and his wife Teresa are "grateful for the time" they spent getting to know Edwards.

"We have many wonderful memories of those days traveling the country and seeing firsthand Elizabeth's great affection for Cate, Jack, and Emma Claire. Today all those moments are rushing back," said Kerry. "The same day our campaign ended at Faneuil Hall, we saw Elizabeth head off to Mass General to confront this terrible disease. America came to know her in a different and even more personal way, as she fought back with enormous grace and dignity. She became an inspiration to so many."

Secretary of State Hillary Clinton also released a statement on Edwards' death, remarking, "America has lost a passionate advocate for building a more humane and just society, for reforming our health care system, and for finding a cure for cancer once and for all."

"But the Edwards family and her legion of friends have lost so much more -- a loving mother, constant guardian, and wise counselor," said Clinton.

The family requests that in lieu of flowers, donations may be made to the Wade Edwards Foundation which benefits the Wade Edwards Learning Lab at www.wade.org.